title: Comparative efficacy of moxidectin 2% equine oral gel and ivermectin 2% equine oral paste against Onchocerca cervicalis (Railliet and Henry, 1910) microfilariae in horses with naturally acquired infections in Formosa (Argentina).
abstract: On the basis of positive skin snips for Onchocerca cervicalis microfilariae (MF), 45 horses were chosen from 48 in a total of 257 screened on 12 locations in the northeast Province of Formosa (Argentina), and randomly assigned to two treatment groups of 20 horses each, and a nontreated control group of five horses. On Day 14 post-treatment (PT), skin snip samples in the ivermectin-treated (0.2 mg/kg) group were negative for normal viable microfilariae (MF), while horses in the control group maintained their pretreatment level of infection. On the same Day in the moxidectin-treated (0.4 mg/kg) group, 18 horses were negative for MF, but the remaining two had a total of 1 and 2 MF, respectively (equivalent to 10 and 20 MF/g of skin), but all three parasites showed marked cuticular and structural damage. Both horses were negative in a repeat biopsy on Day 21. From Day 3 PT, one ivermectin-treated horse (5%) evidenced an approximate 15 x 2 x 3 cm-sized, apparently nonpainful, oedematous swelling on the ventral midline, 20 cm in front of the navel, which remained unchanged on Day 14 PT. Adverse reactions were not observed in the moxidectin-treated group. Parasitaemia was found in 18.7% of sampled horses (48 of 257), and the number of MF varied between 10-1820/g of skin snip (mean 172). Similar prevalence and total counts had been described previously in 1985 and 1986 in cattle-farm horses in the same area of Argentina; in surveys in Texas (1974) and Louisiana (1995) in the USA, infection rates were also similar, but total counts much higher. It is concluded that moxidectin 2% equine oral gel and ivermectin 2% equine oral paste, were equally 100% effective in the control of O. cervicalis MF. Contrary to ivermectin, moxidectin did not cause post-treatment dermal reactions.
authors.affiliation: Department of Parasitic and Infectious Diseases, Faculty of Animal Health and Production, University of Formosa, Argentina.
authors.forename: O A
authors.initials: OA
authors.lastname: Mancebo
authors.forename: J H
authors.initials: JH
authors.lastname: Verdi
authors.forename: G M
authors.initials: GM
authors.lastname: Bulman
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage / Q000627:therapeutic use*; D000900:Anti-Bacterial Agents; D001118:Argentina; D005260:Female; D005782:Gels; D006734:Horse Diseases / Q000188:drug therapy* / Q000469:parasitology; D006736:Horses; D007559:Ivermectin / Q000008:administration & dosage / Q000627:therapeutic use*; D018942:Macrolides / Q000008:administration & dosage / Q000627:therapeutic use; D008297:Male; D009824:Ointments; D009854:Onchocerca / Q000302:isolation & purification; D009855:Onchocerciasis / Q000188:drug therapy / Q000662:veterinary*; D012867:Skin / Q000469:parasitology
chemical_list: D000871:Anthelmintics; D000900:Anti-Bacterial Agents; D005782:Gels; D018942:Macrolides; D009824:Ointments; D007559:Ivermectin; C027837:moxidectin